Meaning: 'Discovered' means to find something that was previously unknown or hidden.

Wrong options:

• invented: 'Invented' implies creating something new, which does not fit as the team found a species that already existed.
• find: 'Find' is in the base form and does not match the past tense required in this context.
• unearths: 'Unearths' is present tense and does not fit the past context of the sentence.
• stumble: 'Stumble' suggests a casual or accidental finding, which contradicts the deliberate effort described in the sentence.
• occupied: 'Occupied' refers to taking up space or being in a place, which does not relate to the action of discovering a species.

Correct answer: stumble

Explanation: The verb 'stumble' fits the context as it conveys the idea of finding something by chance, which contrasts with the careful methods the scientists used. It is in the base form, which is appropriate following 'didn't just'.

Meaning: 'Stumble' means to come across something unexpectedly or by accident.

Wrong options:

• discovered: 'Discovered' is the correct answer for the first blank and does not fit here as it implies a deliberate finding.
• possessed: 'Possessed' refers to having something, which does not relate to the act of finding.
• invented: 'Invented' implies creating something new, which does not fit the context of finding a species.
• find: 'Find' is in the base form and does not match the structure of the sentence after 'didn't just'.
• unearths: 'Unearths' is present tense and does not fit the past context of the sentence.
• occupied: 'Occupied' does not relate to the act of finding and is irrelevant in this context.

Correct answer: possessed

Explanation: The verb 'possessed' is in the past tense and correctly describes the biologists' extensive knowledge. It fits grammatically and contextually as it indicates that the biologists had this knowledge at the time of the research.

Meaning: 'Possessed' means to have or own something, in this case, knowledge.

Wrong options:

• discovered: 'Discovered' is the correct answer for the first blank and does not fit here as it refers to finding something.
• stumble: 'Stumble' refers to finding something by chance, which does not relate to knowledge.
• invented: 'Invented' implies creating something new, which does not fit the context of having knowledge.
• find: 'Find' is in the base form and does not match the past tense required in this context.
• unearths: 'Unearths' is present tense and does not fit the past context of the sentence.
• occupied: 'Occupied' refers to taking up space or being in a place, which does not relate to having knowledge.

Correct answer: hailed

Explanation: The verb 'hailed' is in the past tense and fits the context as it describes how the scientific community reacted to the findings. It indicates a positive acknowledgment of the discovery.

Meaning: 'Hailed' means to publicly praise or acclaim something.

Wrong options:

• discovered: 'Discovered' is the correct answer for the first blank and does not fit here as it refers to finding something.
• possessed: 'Possessed' refers to having something, which does not relate to the reaction of the scientific community.
• invented: 'Invented' implies creating something new, which does not fit the context of acknowledging a discovery.
• stumble: 'Stumble' refers to finding something by chance, which does not relate to the reaction of the scientific community.
• unearths: 'Unearths' is present tense and does not fit the past context of the sentence.
• occupied: 'Occupied' does not relate to the act of praising or acknowledging a discovery.